Photographic developer



Patented Sept. 5, 1939 172,210 rno'roonarmc nnvnmrnn Alfred Miller, Dessan, Germany, assignor, by

mesne assignments, to Agra Ansco Corporation, Binghamton, N. Y., a corporation of Delaware No Drawing. Application October 27, 1988, Be-

a)? No. 237,281. In Germany October 29,

1 Claim. (01. 95-48) The present invention relates to photographic developers and more particularly to developers comprising additions which prevent the precipitation of lime salts from the solutio It has been proposed to prevent the precipitathe concentrated developing solutions or also to 6 tion of lime salts from photographic solutions, e'sthe commercial dry mixtures of the development pecially developers, which have a considerable chemicals. content of salt and which have been prepared The following examples serve to illustrate the with water with a high content of calcium by invention without, however, limiting the scope adding to the solutions alkali metal-metaor thereof to the specific details set forth therein. 10 ipyro-phosphates. This addition loses its action Example 1 11 solutions which are subjected to prolonged use for instance in tank developers: after a certain To a developer of the following composition' time separation of flocks occurs which is probably 1'methylammo'hydmxybenzenesulfate due to a slow decomposition of the phosphates 15 and to the precipitating action of gelatin parsodiumsulfite cryst 40 ticles which may get into the tank developer Sodiumcarbonati 20 during development. The flocculation of mm Potassium bmmlde sediments from the solutions can of course be Water 7""7 1000 avoided permanently by the addition of aliphatic there are added either in solution or to the solid nitrogen containing polycarboxylic acids or salts mlxture of mammals grams of thereof. polycarboxylic acids of this kind are metaphosphate and 2.5 grams of trlmethylamine for instance described in Annalen, 122, pages trica'rboxy 11c acid I 269 and 276, and Annalen, 278, pages 231 and Example 2 234, furthermore in the German Patent No. A developer t e foll w OOmPOSitIOHZ 638,071 and in the French Patent No. 804,497. 1-methylamino-4-hydroxybenzenesulfate When employing developers having these addigram..- 1 tions it is sometimes possible, that by injudicious Hydroquinone grams 6 handling, especially of photographic materials Sodiumsulfite' cryst do 52 with ammonia emulsions, separation of lime crys- Potassiu carbonate do 30 30 tals occurs in the emulsion layer itself. Although Potassium bromide gram 1 this so-called lime fogging which consists of Water -2. cc 1000 very fine crystals of calcium salts is readily soluble there are added either to the solution or to thein strongly acid fixing baths or in dilute acetic or mixture of the solids 0.5 gram sodium hexametahydrochloric acid, the dissolution of the fogging phosphate and 1.5 grams tetramethyldiamino- 35 represents a lengthy and complicated process step a e a y dwhich is avoided by the employment of the im- Ewample 3 proved developer of the present invention.

I have found that suitable mixtures of metaor To a developer of the following composition pyrophosphates with the aliphatic nitrogen con- Hydmqumone 3 40 taining polycarboxylic acids or their salts, if Sodiumsulflte 60 added to the developing so1utions,'prevent the Sodiumcarbonate 2 flocculation of lime salts in the solution and the sodiumtetrabomiie 4 so-called "lime fogging of the emulsion. The Potfi'ssium bromlde action of the mixture is not merely aggregative Sodmm salt of citric acid 3 45 but the co-operation of the two additions results in there a e ad d 2 grams of Sodium e ametaan improvement of high practical importance P o p at and 2 grams 6t y since it appears that the presence of the aliphatic diethylamine-dicarboxylic acid. For use the denitrogen containing polycarboxylic acids and veloper must be dissolved in 1000 cc. of water. their salts prevent the formation of decomposi- I claim: 60 tion products from metaor'pyrophosphates and A photographic developer comprising a dethereby the formation of flocks. veloping agent, an efiective amount of an alkali It is possible to employ the compounds in quesmetal salt of an acid selected from the group contion in the form of their free acids or as soluble 'sisting of meta-phosphoric acid and pyrophossalts, especially as alkali metal salts. The phoric acid and an eifective amount of an amounts which have to be employed depend upon the composition of the developer per se and of course also on the lime content of the water. used for dilution or solution. The mixtures of metaor pyrophosphates and aliphatic nitrogenous poly.. carboxylic acids and their salts may be added to aliphatic nitrogen containing polycarboxylic acid.

. ALFRED MEIER. 

